Telephone-exchange system.



PATENTED OCT. 24, 1905.

H. G. WEBSTER.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED FEIB.14. 1903.

ITIVETTEIF WET 2) E E EFF u RHUFUEBH Be it known that 1, HARRY Gr.WnBs'rnR, a relay is in its normal unattracted position, the citizen ofthe United States, residing at Ghienergization of the line-relay causesan actuacago, in the countyof (look and State of Illitionof its armatureto close circuit through nois, have invented a certain new and usefulthe line-signal lamp and switch-contacts of Improvement in TelephoneExchange Systhe cut-oif relay. The connection of the cord tems, of whichthe following is a full, clear, connecting apparatus with theline whosesig- 6O concise, and exact description, reference benal-larnp has beencaused to glow causes the ing had to the accompanying drawings,formclosure of a circuit of decreased resistance ing a part of thisspecification. through one winding of the cut-oi? relay, My inventionrelates to telephone-exchange whereby the balanced differentialenergization systems, and particularly to systems in which of thecut-01f relay is destroyed to cause an 5 a common source ofcurrentlocated at the cenenergization thereof and a consequent actuatralstation is employed to furnish current both tion of the armature ot' thecut-off relay. The for the operation of the necessary signalingactuation of this armature serves to break the apparatus and thesubstation-transmitters local circuit through theline-signallamp. The

My invention relates more particularly to cord-circuit adapted for usein connection with such systems in which a so-called diiferentheline-circuit thus described may be of any tial cut-oli' relay may beemployed. suitable design adapted to cause the proper My inventionprovides a system in which operation of the differential cut-0d relayand there are no relay-contacts included in the to serve the customaryuses of cord connecttalking-circuit. The limbs of the telephoneingapparatus in connecting for conversation 7'5 line extending fromasubstation to an exany desired substations. change are permanentlyconnected with the My invention will be best understood by terminals ofthe common source of current. reference to the accompanying diagrammaticThe well-known spring-jacks employed in drawing, in which at each of thesubstations making connections between subscribers may A and B is showna common form of substabe permanently connected with the telephonetionapparatus comprising a switch-hook 1, lines, whereby a system ofgreatsimplicity adapted when in its normal depressed posiand reliabilityin operation is secured. tion, due to the weight of the receiver 2, toMy invention also provides improved means serially connect in circuitwith the limbs 3 and whereby a central-station operator may test 4 ot'the telephone-line the calling signal-bell the operative condition of asubscribers line 5 and the condenser 6. Upon the removal to know whetheror notitis busy. The mech of the receiver from the switch-hook thelatanism associated with the cut-oft relay comter assumes a positionadapted to close a cirprises a single armature and back contact cuitbetween the telephone-limbs 3 and 4: therefor. through abattery-transmitter T and the priin accordance with my invention Iprovide mary 8 of an induction-coil, whose secondary at the centralstation a common source of cur- 9 is connected with the receiver 2. Thelimbs rent, to opposite terminals of which the two 3 of thetelephone-lines extend each to the limbs of a line from each substationare persubstation and there through a winding 10 of manently connected,one limb serially includthe differential relay 11 to the positivegrounding a line-relay and a coil of a diiierentiallyed terminal of thecommon battery 12. The wound cut-oii' relay, the other limb includinglimbs 4 of the telephone-lines extend each to the other coil of thediiferential relay. the negative pole of the battery 12, there be- Themultiple spring-jacks used in connecing serially included in each ofsaid limbs the tionwith the customary cord-circuit in conwinding 13 ofthe dilierential relay 11 andwo 'necting subscribers are permanentlyconnectthe winding of a line-relay 14:. The answered with the limbs ofthe telephone-line between ing-jack 15 and the multiple calling-jacks 16thesubstation and the cutoii' and line relays. 16 are permanentlyconnected with the tele- Aline-signal is. provided,desirably in the formphone-line, as shown, the tip contacts 17 17 of a small incandescentlamp, whose local cirbeing shown in this instance connected with To allwhom it mag concern:

cuit is jointly controlled by the line and cutnurr nn STATE$FENT OFFICE.

HARRY G. WEBSTER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE STRON-BERG-OARLSON TELEPHONE MANUFACTURING COMPANY, OF ROCH- ESTER, NEW YORK,AGORPORATION OF NEWV YORK.

TELEPHONE-EXCHANGE SYSTEM- Specification of Letters Patent. Applicationfiled February 14,1903. Serial No. 143,304.

No. 802,671. Patented Oct. 24, 1905.

ofi' relays. When the armature of the cut-oif the limb 4, while thesleeve-contacts and thirnblcs 18 18 are connected with the limb Aline-signal lamp 19 is adapted to be illuminated through a local circuitcontaining the battery 12, the continuity of this circuit being jointlycontrolled by switch-contacts of the cut-01f relay and the line-relay.'lVhen the armature 20 of the cutoff relay is in its normal unattractedposition, the energization of the line-relay 14: causes the attractionof its armature 21 to cause the closure of the local circuit adapted toilluminate the lamp 19. The energization of thecut-oif relay causes theattraction of the armature 20 to break this circuit.

The cord-circuit employed is shown as comprising an answering-plug 22and a callingplug 23, whose tip-contacts are suitably connected througha cord-strand 24, including the condenser 25,and whose sleeve-contactsare normally connected through the sleevestrand 26.

The customary ringing and listeningkey 27 is provided, a manipulation ofthis key in one direction serving to connect the opera- 5 tors telephoneset 28 in bridge of the cordcircuit, while a manipulation of the key ina reversed direction serves to connect the ring ing-generator 29 betweenthe cord-strands 24 and 26, leading to the calling-plug 23.

A circuit in shunt of the condenser 25 includes the supervisory rela s30 and 31, the common terminal of which is connected through aresistance 32 with the negative pole of the common battery 12. Asupervisory controlling-relay 33 is connected between the negative poleof the battery 12 and the sleevestrand 26 of the cord-circuit. Thearmature 3 1 of this supervisory controllingrelay when in its attractedposition, as shown, serves to connect the positive pole of the battery12 with the supervisory signal-lamps 35 and 36, the continuity of thecircuit through the lamp 35 being established through the armature 37 ofthe supervisory relay 30 when in its normal unattracted position, andthe continuity of the circuit through the supervisory signallamp 36being similarly established by the armature 38 0f the relay 31.

The operation of my improved system may be described as follows: Theremoval of the receiver at substation A from its switch-hook causestheclosure of a' circuit, which may be traced as follows: from thepositive pole of the battery 12 through the coil 10 of the differentialrelay and the limb 3 of the telephone-line to the transmitter andprimarywinding of the induction-coil at the substation A through the limb 4 ofthe telephoneline, the winding 13 of the differential cut-ofi" relay,and the winding of the line-relay 14, to the negative pole of thebattery 12 The closure of this circuit does not cause the actuation ofthe armature of the cut-off relay on account of the difierentialrelation of the windings 10 and 13. The closure of the circuit throughthe line-relay. however, causes the attraction of its armature to closethe'local battery-circuit through the line-signal 19. The operatorapprehending the signal given by the illumination of the lamp 19 insertsthe answering-plug 22 within the answering-jack 15, thereby connectingher cord-connecting apparatus in circuit with the limbs 3 and L of theline leading to substation A. The insertion of the plug 22 immediatelycauses the closure of a circuit, which may be traced as follows: fromthe positive pole of the batter 12, through the winding 10 of thedifferential cut-off relay 11, to the sleeve-spring 18 of the,answering-jack. 15, to the sleeve-contact of the plug 22, through thesleeve-strand 26 and the winding of the supervisory controlling-relay33, to the negative pole of the battery 12. Thus a circuit of decreasedresistance is closed through the winding 10 of the differential cut-offrelay, causing a net energization of the relay-core, whereupon thecut-off relay-armature 20 is attracted from its back contact connectedwith the ground, as shown. Since the local circuit adapted to cause theillumination of the lamp 19 includes the ground connection between theback contact of the armature 20 and the groundedside of the battery' 12,this actuation of the cut-off relay-armature breaks the local circuitthrough the linesignal 19, whereupon the,- lamp is extinguished. Thiscircuit established hythe insertion of the plug within a jack alsocauses the energization of the relay 33 to attract its armature 3 1,whereupon the supervisory sig:

nal-lamps 35 and 36 are connected with the positive pole of the battery12. The armature 38 of the cut-off relay 31 being in its normalunattracted position completes the circuit through the lamp 36,whereupon thisv supervisory signal-lamp is caused to glow. The receiverat the substation A being removed from its hook, closes a circuitthrough the supervisory relay 30, which may be traced as follows: fromthe negative pole of the battery 12, through the resistance 32, thesupervisory relay 30, the tip-strand. 24 of the cordcircuit, thetip-contact of the answering-plug 22, the tip-spring of theanswering-jack 15, the limb 4 of the telephone-line, the primary coil 8,the transmitter 7, the limb 3 of the telephoneline, and the winding 10of the cut-off relay. The consequent energization of the relay 30 causesthe attraction of its armature 37 to open the otherwise completedcircuit through the supervisorysignal-lamp 35. This lamp,which isintended to apprise the operator of the operative condition of thesubscribers substation apparatus is therefore not permitted to glow uponthe insertion of the answeringplug within the answering-jack, Theoperator manipulates her listening-key to connect her telephone set inbridge of the cord-circuit connected with the calling-substation.

Upon ascertaining that the subscriber at subscriber at substation relay33 and the coil of the differential cut-off relay associated with thetelephoneline running to substation B. An actuation of the armature ofthis cut-ofi' relay is thereby caused to immediately open a circuit,which otherwise might be closed through the line-signal19,'corresponding to the substation B. Upon the removal of the receiverat substation B from its switch-hook a circuit is closed through thesupervisory relay 31, the

3 the attraction of consequent'energization of this relay causing thearmature 38 to extinguish the lamp 36. Either subscriber upon finishingthe conversation with the other replaces his receiver upon itsswitch-hook, thereby opening thepreviously-traced circuit through thecorresponding supervisory relay or 31, as the case-may be. The armature34 of the supervisory controlling-relay 34 being still in its abnormalattracted position,

due to the continuance of the insertion of the plugs within theline-jacks, the release of an armature 37or 38 of the supervisory relaycauses the closure of the local circuit through the correspondingsupervisory signal-lamp 35 or 36, whereby the latter is caused to glow,thereby giving the operator a signal that the connecting-plug may bewithdrawn from the corresponding line-jack. The removal of thecord-connecting plug causes the restoration of the line and cut-offrelays to their normal condition. Upon the removal of both plugs thesupervisory relays and the supervisory controlling-relay 33 are alsorestored to their normal condition. i

' he means employed by an operator to see before inserting a plug withina jack is as follows: It

will be seenthat upon the manipulation of the listening-key to connectthe operators telephone set in bridge of the cord-circuit the connectionthrough the supervisory relay 31 between the negative pole of thebattery and the tip-strand 24. of the cord-circuit is broken.

There is connected with the contact39 a conductor leading through atest-winding 40 in inductive relation with,the induction-coil of theoperators telephone set to the grounded side of the battery 12.

It will be seen that under normal conditions in which the line runningto substation B is -not in use the test-contacts 18 of the associatedmultiple jacks are connected-with the grounded side of the batterybyconductors eludes the coil 10 of the potential above that through which'no current is flowing, and

therefore these test-contacts are at the zeropotential of the ground.Upon the insertion of a plug of a cord-circuit within any pf 'themultiple-jacks a circuit is closed which inassociated cut-off relay andthe coil of a supervisory controlling-- relay 33. The test-contacts areall connected with this circuit. Upon the connection of the cord-circuitwith a-line all of the associated test-contacts are therefore raised inof the ground. 'While the tip-strand of an idle cord-circuit is normallyat the potential of the negative terminal of the common battery, stillupon the manipulation of the listening-key the connection between thepart of the tip-strand leading to the testing-tip contact and thenegative side of the battery is brolzen, and ,t is part of thetip-strand is connected ,through' the test-winding 40 with the positivegrounded side of the battery flows through the cord-circuit and when thelistening-key is thus manipulated, the tipof the calling-plug 23 ischarged to thezero potential of the grounded side of the battery 12. Inmaking a test of a line when the testthimbles are at the zero potentialof the ground no current will be caused to flow between the testing-tipcontact and the test-thimble. Therefore no clickwill be heard in theoperators receiver, the operator knowing thereby that the tested line'isidle. If,on the other hand, the line is busy and, as previouslydescribed, the test-thimbles have been raised in potential above that ofthe ground, the connection of the tip of the calling-plug and atestrthimble will cause a current to flow through the testwinding 40,which induces a current in the secondary winding of the induction-coilconnected with-the operators telephone, whereupon a click in theoperators receiver notifies her of the busy condition of the testedline.

W hile I have herein shown and described one particular embodiment of myinvention, it will be apparent to those skilled in the art that manymodifications thereon may be made without departing from the spiritof myinvention. I do not, therefore, .wish to limit myself to the precisedisclosure herein set forth; but,

Having described my invention, Y. claim as new and desire to secure byLetters Patent- 1. In a telephone-exchan ge system, the combination witha telephone-line extending by its 12. When no current limbs from asubstation to an exchange, of a source of current at the exchange, tothe terminals of which are permanently connect-ed the limbs of saidline, a line-relay permaing saidline with another for convcrsation,andmeans whereby the connection of saidv cord connecting apparatus withsaid line causes an actuation of said cut-off relay to destroy thesubstation control of the line-signal. ,2. In a telephone-exchangesystem, the combination with a telephone-line extending by its limbsfrom a substation to an exchange, of a source of current at theexchange, to the terminals of which are permanently connected the limbsof said'lines, aline-relay serially included in circuit with one of saidline-limbs, a difierential cut-ofi relay having two windings, eachpermanently serially included in a limb of said line, a line-signaljointly controlled by said line and cut-ofi' relays, cord connentin gapparatus for connecting said line with another for conversation, andmeans whereby the connection of said cord connecting apparatus with saidline causes an actuation of said cut-off relay to destroy the substationcontrol of the line-signal.

3. In a telephone-exchange system, the com bination with atelephone-lineextending by its limbs from a substation to an exchange, of a source ofcurrent at the exchange, to the terminals of which are permanentlyconnected the limbs of said line, a line-relay permanently included incircuit with one of said line-limbs, a differential cut-0E relay havingtwo windings, each permanently included in a limb of.

said line, a line-signal jointly controlled by said line and cut-offrelays, cord connecting apparatus for connecting said line with anotherfor conversation, and means whereby the connection of said cordconnecting apparatus with said line causes an actuation of said cut-oftrelay to destroy the substation control of the line-signal,

,- 4. Inatelephone-exchangesystem,thecombination with a telephone-lineextending by its i limbs from a substation to an exchange, of'a, sourceof current at the exchange, to the ter-' minals of which are permanentlyconnected the limbs of said'lines, a line-relay included in circuit withone of said line-limbs, a differential cut-ofi relay having twowindings, each permanently included ina limb of said line, a

i line-signal jointly controlled by said line and cut-off relays, cordconnecting apparatus for connecting said line with anotherforconversation, and means whereby the connection of said cordconnecting apparatus with said line,

causes an actuation of said cut-off relayv to de-,

stroy the substation control of the line-signal. 5. In atelephone-exchange system, the combination with a telephone-lineextending by its limbs from a substation to an exchange, of a source ofcurrent as the exchange, to the terminals of which are permanentlyconnected the limbs of said line, a line-relaypermanently seriallyincluded in circuit with one of said line-limbs, a differential cut-offrelay having two windings, each serially included in a limb of saidline, a line-signal jointly controlled by said line and cut-01f relays,cord connecting apparatus for connecting said line with another forco'nversatiomand means whereby the connection of said cord connectingapparatus with said linecauses an actuation vof said cut-01f relay todestroy theflsubstation control of the line-signal.

6. I In a telephone-exchange system, the com bination with atelephone-line extending by its limbs from a substation to an exchange,of'a source of current at the exchange,to' th eterminals of whichare-permanently connected the limbs of saidline, a linewrelaypermanently serially included in 'circuitgwith one of .said line-limbs,a differential cut-off relay hay us,

two windings permanentlyserially included in circuit with atelephone-line, a line-signal jointly controlled by said line andcut-olf'relays, cord connecting apparatusfor connecting said line withanother forconversation, means whereby the connection or said,cordc'onnecting apparatus with said line causes an actuation of thesaid cut-off relay to destroy the substation control ofthe line-signah I7 In a telephone-exchange system, thecombination with a telephone-lineextending its limbs from a substationto. an'exchangej of a source ofcurrentat the exchange, to the tervminals of which are permanentlyconnected the limbs of said line, a line-relay included in circuit withone limb of said line, a cut-off relay having two differential windingsserially included in thelimbs of said line, a line-signal jointlycontrolled by saidline and cut-0E relays, cord connecting apparatus forconnecting said line with another for conversation, and means wherebythe connection of said cord connecting apparatus with said line causesan'actuation with said cut-off. relay to destroy the substation controlof the line-signa I 8. In a'telephone-exchange,the combination with atelephone-line extending by its limbs from a substation to an exchange,of a source of current at the exchange, to the terminals or'which areconnected the limbs of said line, a line-relay permanentlyiincluded. ina linecircuit, a cut-ofi relay having two differential windings, eachpermanently serially included in a limb of saidline, a line-signaljointly controlled by said line and -cut-ofi relays, cord connectingapparatus for connecting said line with another for conversation and].means whereby theconnection ofsaid cord-connecting apparatus with saidline causes an actuationof said cut-0c relay toidestroy the substationcontrol ofsaid line-signal, i

j 9. Inatel'eph"neyexchangesystem, the combination with a telephone-lineextending by its limbs from a substation toanexchange, of a source ofcurrent at the exchange, ,to the terminals of which are vpermanentlyconnected the limbs of said line, a line-relay permanently seriallyincluded in circuit with one of said line-limbs, a difi'e'rentialcut-oif .relaylhaving 5 of decreased its limbs from a substation to anexchange,

of a source of current at the exchange, to the terminals of which arepermanently connected the limbs of said line, a line-relay seriallyincluded in circuit with one of said line-limbs, a difierentialcut-otl'rela'y having two windings, each permanently serially includedin a limb of said line, a line-signal jointly con,- trolled by said lineand cut-ofi' relays, cordconnecting apparatus for connecting said linewith another for conversation, and means whereby the connection of saidcord connecting .apparatus with said line closes a circuit resistancethrough one winding of said cut-ofl? relay to cause an actuation otherfor conversation,

thereof.

1 1. In a telephone-excl] ange system, the combination with atelephone-line extending by its limbs from a substation to an exchange,of a source of current at the exchange, to the terminals of which arepermanently connected the limbs of said line, a line-relay permanentlyincluded in circuit with one of said line-limbs, a diiferential cut-offrelay having two windings, each permanently included in a limb of saidline, a line-signal jointly controlled by said line and cut-ofi relays,cord connecting apparatus for connecting said line with anand meanswhereby the connection of said cord connecting apparatus with said linecloses a circuit of decreased resistance through one winding of saidcut- 0E relay to cause an actuation thereof.

12. In atelephone-exchange system,the combination with a telephone-lineextending by its limbs from a substation to an exchange, of a source ofcurrent at the-exchange, to the terminals of which are permanentlyconnected the limbs of said line,'a line-relay included in circuit with-one of said line-limbs, a differenversation, and means whereby tialcut-off relay having two windings, each permanently included in a' limbof said line, a line-signal jointly controlled by said line and cut-oflrelays, cord connecting apparatus for connecting said line with anotherfor conthe connection of said cord connecting apparatus with said lineclosesa circuit of" decreased resistance through one winding of saidcut-oif relayto cause an actuation thereof.

13. In a telephone-exchange system, the combin'ation-withatelephone-line extending by its limbs fromia substation to an exchange,

of a source of current at the exchange, to the terminals of which arepermanently connected the limbs of said line, a line-relay permanentlyserially included in circuit with one of said line-limbs, a diiferentialcut-01f relay having two windings, each serially included in a limb ofsaid line, a line-signal jointly controlled by said lineand cut-otfrelays, cord connecting apparatus for connecting said line with anotherfor conversation, and means whereby the connection of said cordconnecting apparatus with said line closes a circuit of decreasedresistance through one winding of said cut-ofl relay to cause anactuation thereof.

14. In a telephone-exchange system, the combination with atelephone-line extending by its limbs from a substation to an exchange,of a source of current at the exchange, to the terminals of whichareperman ently connected the limbs of said line, a line-relaypermanently serially included in circuit with one of said line-limbs,adilierential cut-ofl relay having two windings permanently seriallyincluded in circuit with a telephone-line, a line- ,signal jointlycontrolled by said line and cutoff relays, cord connecting apparatus'forconnecting said line with another for conversation, and means wherebythe connection of said cord connecting apparatus with said line closesacircuit of decreased resistance through one winding of said cut-offrelay to cause an actuation thereof.

15. In a telephone-exchange system, the combination with atelephone-line extending by its limbs from a substation to an exchange,of a source of current at the exchange, to the terminals of which arepermanently connected the limbs of said line, a line-relay included incircuit with one limb of said line, a cut-off relay having twodifierential windings serially included in the limbs of said line, alinesignal jointly controlled by said line and cutoff relays, cordconnecting apparatus for connecting said line with another forconversa-' tion, and means whereby the connection of said cordconnecting apparatus with said line closes a circuit of decreasedresistance through one winding of said cut-ofl' relay to cause anactuation thereof.

16. In a telephone exchange,the combination with a telephone-lineextending by its limbs from a substation to an exchange, of a source ofcurrent at the exchange, to theterminals of which are connected thelimbs of said line, a line-relay permanently included in a line circuit,a cut-off relay having windings, each permanently serially included in alimb of said line, a line-signal jointly controlled by said line andcut-off relays, cord connecting apparatus for connecting said line withanother for conversation, and means whereby the connection ing apparatuswith said line closes apircuit of decreased resistance through onewinding of said cut-ofirelay-to cause anactuation thereof.

of said cord connect- 1 2 two diiferential 17. In a telephone-exchangesystem, the combination with a telephone-line extending by its limbsfrom a substation to an exchange,

, of a source of current at the exchange, to the R terminals of whichare permanently connected the limbs of said line, a spring-jack havingcontactspermanently connected to the limbs of said line, a line-relaypermanently serially included in circuit with one of said line-limbs, adifi'erential cut-ofi relay having two windings, each permanentlyserially ineluded in a limb of said line, a line-signal jointlycontrolled by said line and cut-01f relays, cord connecting apparatusfor connectand means whereby the connection of said cord connectingapparatus. with said line causes an actuation of said cut-elf relay todestroy the substation control, of the linesignal.

18. In a telephone-exchange system, the combination with a telephoncline extending by its limbs from a substation to an exchange,

, of a source of current at the exchange, to the terminals of which arepermanently connected the limbs of said lines, a spring-jack havingcontacts permanently connected to the limbs of said line, a linerelayserially included in circuit with one of said line-limbs, adifl'erential cut-oil relay having two windings, each permanentlyserially included in a limb of said line, a line-signal jointlycontrolled by said line and cut-off relays, cord connecting apparatusfor connecting said line with another for conversation, and means wlereby the connection of said cord connecting apparatus with said linecauses an actuation of said cut-off relay to destroy the substationential cut-ofi' relay having two windings, each i 5 \permanentlyincluded in a limb of said line,

a line-signal jointly controlled bysaid line and cut-ofi' relays, cordconnecting apparatus for connecting said line with anotherfor-conversation, and means whereby the connection of said cordconnecting apparatus with said line ,stroy the substation control of theline-signal.

20. In a telephone-exchange system, the

, combination with a telephone-line extending by its lim bs from asubstation to an exchange, of a source of current at the exchange, tothe terminals of which arepermanentIy connected ,th 1i,mlQS.Of saidline, a spring-jack having ,qcontacts permanently'connected to the limbsL 5 of said lline, a line -relay included in circuit ing said line withanother for conversation,

causes an actuation of said cut-oft relay to deconnected to the llmbs ofsaid line, a line-rewith one of said line-limbs, a differential cutofirelay having two windings, each permanently included in a limb of saidline, a linesignal jointly controlled'by said line and cutoff relays,cord connecting apparatus for connecting said line with another forconversation, and means whereby the connection of said cord connectingapparatus with said line causes an actuation of said cut-off relay todestroy the substation control of the line-signal.

21. In a telephone-exchange system, the combination with atelephone-line extending by its limbs from a substation to an exchange,of a source of current at the exchange, to the terminals of which arepermanently connected the limbs of said line, a spring-jack havingcontacts permanently connected to the limbs of said line, a line-relaypermanently serially included in circuit With one of said line-limbs, adifl'erential cut-off relay having two windings, each serially includedin a limb of said line, a line-signaljointly controlled by said line andcut-off relays, cord connecting apparatus for connecting said line withanother for conversation, and means whereby the connection of said cordconnecting apparatus with said line causes an actuation of said cut-offrelay to destroy the substation control of the line-signal.

22. In a telephone-exchange system, the combination with atelephone-line extending by its limbs from a substation to an exchange,of a source of current at the ex change, to the terminals of which arepermanently connected the limbs of said line, a spring-jack hayingcontacts permanently connected to the limb of said line, a line-relaypermanently serially included in circuit with one of said line-limbs, adifi'erential cutoff relay having two windings permanently seriallyincluded in circuit with a telephoneline, a line-signal jointlycontrolled by said line and cut-oil relays, cord connecting apparatusfor connecting said line with another for conversation means whereby theconnection oi said cord connecting apparatus with said line causes anactuation of the-said cutoff relay to destroy the substation control ofthe line-signal.

23. In a telephone-exchange system, the combination with atelephone-line extending by its limbs from a substation to an ex.change, of a source of c nrrent at the exchange, to the terminals ofwhich are permanently connected the l mbs of said hne, a springack havmgcontacts permanently lay included in circuit with one limb of said line,a cut-off relay having two differential windings serially included inthe limbs of said line, a line-signal jointly controlled by said lineand cut-off relays, cord connecting apparatus for connecting said linewith another for conversation, and means whereby the connection of saidcord connecting appathe limbs of. said line, a line-relay permanentlyincluded in a linecircuit, a cut-off relay having two differentialwindings, each permanently serially included in a limb of said line, aline-signal jointly controlled by said line and cut-oft relays, cordconnecting apparatus for connecting said line with another forconversation, and means whereby the connection of said cord connectingapparatus with said line causes an actuation of said cut-off rela todestroy the substation control of said line-signal.

25. In a telephone-exchange system, the

combination with a telephone-line extending byitslimbsfrom a substationto an exchan e, or a source of current at the exchange, to t e terminalsof which are ermanently connected the limbs of said ine, a spring-jackhavin tip and sleeve contacts permanently directy connected with thelimbs of said line, a line-relay permanently serially included incircuit with one of said line-limbs,

a differential cut-ofl relay having two windin s,,each permanentlyserially included in a" imb of said line, a linesignal jointly line andcut-oil relays, cordconnecting apparatus for connectin said line withanother for conversation, and means whereby the connection of said cordconnecting apparatus with said line closes a circuit of decreasedresistance through one winding of said cut-0H relay to causean'actuation thereof.

26. In a telephone-exchange system, the

combination with a telephone-line extending its limbs froma substationto an exchange, of a source of current at the 'exchange,'to theterminals of which are permanently connected the limbs of said line, aspring-jack having tip and sleeve contacts ermanently directly connectedwith the lim s of said line, a line relay serially included in circuitwith one of said line-limos, a difierentia cut-off relay having twowindings, each permanently serially included in .a-limb of said line, alinesifgnal jointly controlled by said line and out o relays, cordconnecting apparatus combination with a telephone linc extending forconnecting said line with another for converby its limbs fromasubstation to an exchan e, of a source of current at the.exchango;to t1e terminals of which are permanently connect-. ed the limbs of saidline, a spring-jack having tip and sleeve contacts ermanently directlyconnected with the liml is of-said line, a linerelay ermanently includedin circuit with one 0 said line-limbs, a differential cut-off relayhavin nentl inclu ed in a limb 0 said line, a linesiigna jointlycontrolled by said line and cut 0 relays, cord connecting apparatus forcontion, and means whereby the connectionof said cord connecting aparatus with said line closes a circuit of ecreased resistancethrough'one winding of said cut-off relay to cause an actuation thereof.

combination with a telephone-line extending by its limbs from asubstation to an exchan e, oi' a source of current at the exchange, to te terminals of which are permanently connected the limbs of said line,aspring-jack having tip and sleeve contacts permanently directlyconnected with the limbs of said line, a line-relay included incircuitwithone of said line-limbs, a differential cut-off relay havintwo windings, elude in a limb ofsaid line, a line-signal jointlycontrolled-by said line and cut-oil" reays, cord connecting a paratusfor connecting said line with anot 'and means whereby. the connectionofsaid cord connecting apparatus with said line closes a circuit ofdecreased resistance through one winding of said cut-off relay to causean actuation thereof. y

29. In a telephone-exchange system, the combination with atelephone-line extending by its limbs fromasubstation to an exchange, ofa source of current at the exchange, to t 1e terminals of which arepermanently connected the limbs of said line, a spring-jack ing tip andsleeve contacts permanently dia line-relay permanently serially includedin tial cut-ofl rela having two windings, each serially include tion,and' means whereby the connection of said cord connecting a paratus withsaid line closes a circuit of ecreased resistance through one winding ofsaid cut-oil? relay to cause an actuation thereof.

30. In a telephone-exchange system, the combination with a telephonelineextending by its limbs from a substation to an exchan e,

terminals of which are permanently connecttwo windin s, each perma-' 28.In a telephone-exchange system, the

rectly connected with the limbs of said line,

circuit-with one of said line-limbs, a difierem necting said line withanother for conversaeach permanently inf er for conversation,

Ioo

hav-j.

signal jointly controlled by said line and cute I o cord connectingapparatus for connecting said line with another ,for conversa-i;

of a source of current at the exchange, to t e rectly connected with thelimbs of said line,

v a lin e-relay permanently serially included-in circuit w th oneof saidline-limbs, a dfierenjtial cutoff relay having two windings permanentlyserially included in circuit with a teleplione line; a line signaljointly controlled bysaid lineandcutbfl relays, cord connecty, ingapparatus for connecting said line with another for conversation, andmeans whereby the connection of said cord connecting apparatus with saidline closes a circuit of .de-

creased resistance through one Winding of said cut-oil relay to cause anactuation thereof. 31. In a telephone-exchange system, the

combination with a telephone-line extending 1 by its limbs from asubstation to an exchange, or a source of current at theexchange, the

terminals of which are permanently connected withjthe limbs of saidline, a spring-jack having tip and sleeve contacts permanently directlyconnected with the limbs ot said line,

' a line-relay included in circuit with one limb of said line, a cut-offrelay having two differ- 3 entialwindings serially includediii the limbsofsaid line, a line-signal jointly controlled by said line'aiid cut oiirelays, cord connecting apparatus for connecting said line with anotherfor conversatiomand means whereby the connection of said cord connectingappara'tus withsaid line closes a circuit of decreased resistancethrough one winding ofsaid cut-off relay to cause an actuation thereof.In a. tele 'ihoiie-exchange, the combinalimbs from a substation to anexchange, of a source of current at theexchaiigc, to the tern'iinals ofwhich are connected the limbs of said line, a spring-jack havingtip andsleeve line, aline-signal jointly controlled by said line and ciit oii'relays, cord connecting apparatus foicoiiiiecting saidline with another,[forconversation,and means whereby the concombinationwith:Melephcme-line extending. byitslinibs iroiii a substation to anexchange,

nectioii of said cord connecting apparatus with said line closes acircuit of decreased resistance through one winding of said cut-oilrelay to cause'zin actuation thereof.

33. In a'telephone-exchange systennthc of a source ofcurrent at the ewhange adapted to supply current to the subsLationtransinit entia'lcut-oif relay permanentlyserially included between oneteriniiial oithelsource oi current'and thelsubstation, a second winding ofsaiddifterential'relay permanently serially inciuded between the otherterminal of the source of current and the substation, a linesignaljointly controlled bv said line and said 'ferential cut-off tion with. atelephi'ine-line extending by its "connected in said line-relay, and atest-contact permacut-ofi' relays, and a spring-jack permanentlyconnected with said line.

3i. In a telephone-exchange system, the

combination with a telephone-line extending.

by its limbsfroma substation to an exchange, of a source'of current atthe exchange adapted to supply current to the substation-transmitters, aline-relay and one winding of a difrelay permanently included betweenone terminal of the source'of current and the substation, a "secondwinding of said differential relay permanently included between theother terminal of the source of current and the substation, aline-signal jointly controlled by said line and said cut-off relays, anda spring jack permanently connected with said line.

35. In a telephone-exchange system, the combination with atelephone-line extending by its limbs from a substation to an exchange,of a source of current at the exchange adapted to supply current to thesubstation-transmitters, a line-relay and one winding of a differentialcut-ofi' relay serially included between one terminal of the source ofcurrent and the substation, a second winding of said difi'erential relayserially included between the other terminal of the source of currentand the substation, a local line signal circuit jointly controlled bythe armatures of said line aiid'said cutoff relays, and a spring-jackpermanently connected with said line.

36 In a telephone-exchange system, the combination with a telephone-lineextending by its limbs from a substation to an exchange, of a source ofcurrent at the exchange adapted to supply current to thesubstation-trans mitters, a line-relay and one winding of a differentialcut-ofi relay included between one terminal of a source of currentandthe substation, a second winding of said diiierential cut-oil relayincluded between the other terininal of the source of current and thesubstation, a local line-signal circuit jointly controlled by thearniatures of said line and said cuto i' relays, andaspring-jackperinanently connected with said line.

37, In a teleglmne-excha'nge system, the

combination wit 1' a telephone-line extending by itslimbs from asubstation to an exchange, of a source of current at the exchangeadapted to supply current to thesubstation-transmitters, a line-relayand one winding of a differential cut-cit relay permanently seriallyinr'aluded in 'Oil'CllitbGtWQOn one terminal of the source-of currentand the substation, a

second winding of said difi'erential' relay peri'nanentlyseriallyincludedv between the other terminal of'the source of currentand the substation, a line-signal jointly controlled by said lineandcut-ofi' relays, a spring-jackhaving a contact permanently with thelimb of'the line included pently connected with the other limb of said38. In a telephone-exchange system, the combination with atelephone-line extending by its limbs from asubstation to an exchange, asource of'current at the exchange adapted to supply current to thesubstation-transmitters,-a line-rela and one winding of a dif- V Tferential cut-ofl re ay'included in circuit between one terminal of thesource of current and the substation, a second winding of said.difierential relay permanently senally in cluded between the otherterminal of the source ofcurre'ntand the substation, alocal line-signalcircuit jointly controlled by the armatures of'said line and cut-offrelays, a spring-jack having a contact fiplrmanently connectedwith thelimb of the e included insaid line-relay, and a test-contact permai'ently connected with the other limb of said me.

v 39. In axtelephoneexchange system, the combination with atelephone-line extending b its limbs from a substation to an exchange,oi a source of current at the exchange adapted to supply current to thesubstation-trans mitters,,a line-relay and one winding of a dif-''ferential cut-ofl' rela permanently serially included in a circuitetween the one termnal of the source of current and the substa tion, asecond winding oi said diilerential reother lim v 40. In atelephone-exchange system, the' lay included between the other terminalof the source of (current and thesubstation, a

line-signal jointly controlled by said line and cut-ofl rela s, aspringzj ack havin a contact Egrmanent y connecte with the mb of thee-included in said line-relay, and a testcontact ermanently of saidline.

combination with a telephone+line extending byits limbs from asubstation to an exchange,

a source of current at the exchange adapted to supply current to thesubstatiomtransmitters, a hne-rela and one winding of a differentialcutoff re ay included in circuit b'etween one terminal of the source ofcurrent andthe substation, a secondwindin of said diiferentin relayincluded between t e other terminal 01 the source of current and the substation, a local line-signal circuit jointly controlled by the armaturesof said line and cutofi relays, a spring-jack havin a contact manentlyconnected with thelimb of the ine included in said line-relay, and atest-contact permanently connected with the other limb of said line.

.41. In a telephone-exchange system, thecombination with atelephone-line extending b its limbs from a substation to an exchange,-

' o a source of current at the exchange adapted to supply current to thesubstation-transmitters, a line-relay and one winding of a differentialcut off relay serially included in circuit between one terminal of thesource of connected with j the current and the substation, a secondwinding of said difierential relay-serially included be tween the otherterminal ofthe source of current and the substation, af localline-signal circuit jointly controlled by. the armature, oi

said line and cut-off relays, a springj ack hav ing acontact permanentlyconnected with one limb of the line included in said line-renected withthe other limb of said line.

i2. In a telephone-exchange system, the combination with atelephone-line extending by its limbs from a substation to an exchange,

voia source of current at the-exchange adaptpermanently connected withthe otherlimb of said line.

43. In a telephone-exchange system, the combination with atelephone-line extendlng lay, andv a testecontact permanently cont 4 bits limbs from a substation to an exchange,

.o a source of current at the exchange adapt ed to'sup ly-current to asubstationtransmitter, a inc-relay and-one winding of adifferentialcut-off relay permanently serially included in one limb of said linebetween one terminal of the source of current and the substation, asecond windin of said difierential' relay ermanently seria included inthe second limb of said line etween the other terminal of the source ofcurrent and a substation, .a line-signal jointly controlled b said lineand cut-off relays, and a spring-jac having one contact permanentlyconnected with said first line-lira between the substation and the lineand cut-01f rela s directly and having a test-contact permanentl irectlconnected with the second limb 0 said line g relay.

44. In a telephone-exchange system, the combination with atelephone-line extending b its limbs from a substation to an exchange,

etween said substation and saidcut-off o a source of current at theexchange adapted to supply current to the substation-transmitters, aline-relay and one winding of? a differential cut-off relay seriallyincluded between one terminal of the source of current and thesubstation, a second winding of said differential relay seriallyincluded etween the other terminal of thesource of current and thesubstation, and a local line-signal circuit of said e and cut-offrelays.

jiglintly controlled by the armatu'res 45. In a telephone-exchangeSy'St0m,' tl:1 :-O

combination with a telephone-lineextending station, and a localline-signal circuit jointly ibyits limbs from a substation to anexchange, controlled by the armatures of said line and of a source ofcurrent atthe exchange adaptsaid cut-off relays. 7 ed to supply currentto the substation-trans- In Witness whereof I hereunto subscribe 5mitters, aline-relay and one winding ofa difmy name this 5th day ofFebruary, A. D. 15

ferenti'al cut-off relay included between one 1903.

terminal of the source of current and the sub- 3 HARRY G. WEBSTER.station, a second winding-0f said differential Witnesses: cut-ofi relayincluded between the other ter- 1 LYNN A. WIL IAMS,

-10 mjnal of-the source of current and the sub- HARVEY L. HANSON.

